Here's the draft summary of the OSL2.0 I promised. Comments
requested. Specifically:
Regarding the patent clause: Sam Hartman, you & Anders Torger (the
upstream licensor) were the only two I saw while going back over the
thread that felt it wasn't a problem. Is my characterization of that
issue fair?
The bigger issue, though, is that I didn't provide a DFSG section for
the first problem. The closest the DFSG comes to prohibiting use
restrictions is #6 ("No Discrimination Against Fields of Endeavor"), but
I'm uncomfortable using that for this issue -- is "deploying software
without providing source" a field of endeavor)?. If "a specific field
of endeavor" is intended that broadly, it should be reworded, IMHO.

"deploying software without providing source" is a field of endeavour,
and we can't discriminate against it, or else no Debian user can produce
proprietary software.

There is no obvious prohibition against forced distribution, either.
The closest we have to that are the Desert island test & the Dissident
test -- but I don't see how those can be applied here. My understanding
of those tests is that they apply to cases of the form "in order to do
X, you must do Y." If Y runs afoul of the test, it is a significant
restriction on X. But what's the X in this case?
Don't misunderstand, I do think that the restriction is non-free (though
I'm interested in arguments to the contrary -- I'm not entirely
certain). But I don't see a way to ground it in the DFSG. Perhaps we
should think about language to add to the DFSG for this kind of case?
If so, we should decide whether this is best understood as a use
restriction or forced distribution, so that we know what to add.
--- Begin DRAFT Debian-legal summary of the OSL ---
The OSL (Open Software License) v2.0 is not a DFSG free license.
- Item #5 "External Deployment" places distribution-like burdens on
deployment. E.g., when the Work is made available over a network
source must be distributed. This amounts to forced distribution (DFSG
??).

This fails the desert island test; if you just manage to put your site
"on the net" but could not put the source code, and is stuck now in the
desert island, without outbound connection, you can not comply. The
desert island test is just a test against forced distribution IMHO.

- Item #9 "Acceptance and Termination" requires the licensee to
acknowledge acceptance of the license. According to the Dissident
Test[1] this is a significant restriction on distribution (DFSG #1).
- Item #6 "Attribution Rights" requires retention of any "Attribution
Notice," even if false. There are no restrictions on what may be
considered an attribution notice, so there are no clear limits on what
materials must be retained. This restricts modification (DFSG #3).
In addition to the above it is likely that item #10 "Termination for
Patent Action" is contrary to the DFSG. Item #10 terminates the license
if you are involved in a suit with a licensor over "a patent applicable
to software", or against anyone else over a patent relating to the Work.
Unfortunately, as of the time of this writing this issue has not been
settled conclusively.

item #11 may be a problem for international users, too.

Suggestions:
If you want a copyleft license for your work debian-legal recommends the
GPL v2.0.